Discarded cigarette filters, in the form of cigarette butts, are a major waste disposal and environmental pollution hazard due to mainly containing cellulose acetate which is non-biodegradable; 5.8 trillion cigarettes are smoked worldwide per annum generating >800 000 metric tons of cigarette butts. Apart from causing litter, cigarette butts contain contaminants such as toxic heavy metals, which can leach into waterways, potentially causing harm to both humans and wildlife. In an effort to turn dangerous waste into high value products, this study explores the valorisation of discarded smoked cigarette filters/butts. We show that porous carbons derived from cigarette butts, via sequential benign hydrothermal carbonisation and activation, are super porous and have ultra-high surface area (4300 m² g⁻¹) and pore volume (2.09 cm³ g⁻¹) arising almost entirely (>90%) from micropores. The carbons also have uncharacteristically high oxygen content associated with O-containing functional groups (COOH, C–OH and CO), and show anomalous behaviour with respect to the effect of activation temperature on porosity, the latter being ascribable to the chemical mix present in cigarette butts and their hydrochar products. Due to the combined effects of high surface area, high microporosity and an oxygen-rich nature, the carbons exhibit unprecedentedly high hydrogen storage capacity of 8.1 wt% excess uptake, and 9.4 wt% total uptake at −196 °C and 20 bar, rising to total uptake of 10.4 wt% and 11.2 wt% at 30 and 40 bar, respectively. The hydrogen storage capacity is the highest reported to date for any porous carbons and attains new levels for porous materials in general. This work also raises the question on whether valorisation can solve the intractable cigarette butt problem.

中文翻译：

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烟头衍生碳具有超高的表面积和前所未有的储氢能力

以烟头形式丢弃的香烟过滤嘴是主要的废物处理和环境污染危害，因为它主要含有不可生物降解的醋酸纤维素。全世界每年吸烟5.8万亿支香烟，产生的烟头超过80万吨。烟头除了会引起垃圾外，还含有诸如有毒重金属之类的污染物，这些污染物可能会渗入水道，从而可能对人类和野生动植物造成伤害。为了将危险废物转化为高价值产品，本研究探索了废弃烟熏过滤嘴/烟头的增值。我们显示，通过连续的良性热液碳化和活化作用，来自烟头的多孔碳具有超高的多孔性，并具有超高的表面积（4300 m ²g ^-1）和孔体积（2.09 cm ³ g ^-1）几乎全部（> 90％）来自微孔。碳还具有与含O的官能团（COOH，C–OH和CO），并且在活化温度对孔隙率的影响方面表现出异常行为，后者归因于烟头及其水炭产品中存在的化学混合物。由于高表面积，高微孔率和富氧特性的共同作用，碳在-196°C和20 bar下表现出前所未有的高储氢能力，过量吸收为8.1 wt％，总吸收为9.4 wt％。分别在30 bar和40 bar下的总摄取量分别为10.4 wt％和11.2 wt％。迄今为止，所有多孔碳的储氢能力都是最高的，并且一般而言，多孔材料的储氢量都达到了新的水平。这项工作还提出了一个问题，即通过增值能否解决棘手的烟头问题。